N-alkyl-4-boronopyridinium halides versus boric acid as catalysts for the esterification of α-hydroxycarboxylic acids
N-alkyl-4-boronopyridinium halides versus boric acid as catalysts for the esterification of α-hydroxycarboxylic acids
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DOI：
10.1021/ol052061d
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发表时间：
2005-10-27
期刊：
影响因子：
5.2
通讯作者：
Yamamoto, H
中科院分区：
文献类型：
--
作者：
Maki, T;Ishihara, K;Yamamoto, H
[图表]对于α-羟基羧酸和醇的等摩尔混合物之间的脱水酯化反应，硼酸是一种高效的催化剂。相比之下，N-甲基-4-碘化硼吡啶(2a)是一种比硼酸更有效的催化剂，在过量乙醇中进行类似的酯化反应。多相催化剂也是一种有效的催化剂，如N-聚苯乙烯结合的4-溴化吡啶，可通过过滤回收。
[GRAPHICS]Boric acid is a highly effective catalyst for the dehydrative esterification reaction between equimolar mixtures of alpha-hydroxycarboxylic acids and alcohols. In contrast, N-methyl-4-boronopyridinium iodide (2a) is a more effective catalyst than boric acid for the similar esterification in excess alcohol. A heterogeneous catalyst, such as N-polystyrene-bound 4-boronopyridinium chloride, is also an effective catalyst and can be recovered by filtration.